Method of establishing bleed lines around designs on printing surfaces



METHOD OF ESTA BLISHING BLEED LINES AROUND DESIGNS ON PRINTING SURFACES Filed June 29, 1950 March 3, 1953 o DOHERTY 2,630,384

OWENG. DOHERTY INVENTOR ATTORNEY Patented Mar. 3, 1953 METHOD OF ESTABLISHING BLEED LINES AROUND DESIGNS N PRINTING SUR- FACES.

Owen G. Doherty, New York, N. Y., assignor, by mesne assignments, to Mergenthaler Linotype Company, a, corporation of New York Application June 29, 1950, Serial No. 171,216

6 Claims.

This. invention relates to the production of printing surfaces and, more particularly, to the production of etched printing surfaces by photomechanical methods.

In the. production of such printing surfaces by photomechanical methods it is common practice to employ a screened photographic reproduction or the design to be printed, this being necessary to break up the printing areas into a multiplicity of ink carrying cells defined by upstanding Walls which serve to Support the doctor blade during the printing operation. In so breaking up the printing areas into a multiplicity of ink carrying ells the outl nes or contours of these areas, instead of being sharp and well defined, are serrated with the result that the printed reproductions lac}; contour definition, This lack of on-- tour definition becomes especially objectionable when coarse screens, of say less than 120 lines per inch, are used, as is frequently the case when the designs are to be printed on textiles and the like. In order to avoid this objectionable feature it is now common practice. to create. a s-o-called bleed line around the contour of each of the printing areas on the printing member.

Various photomechanical methods have already been proposed for producing bleed lines around designs on printing surfaces, but these methods are quite complex, requiring numerous operations, great skill, and consequently considerable expense.

The present invention aims to. avoid these objectionable factors and to so simplify the opera 'tion that better printing surfaces may be produced speedily, accurately, and at; little expense as compared with the more. complicated proc dures heretofore employed.

For a. complete description as to how the impr ved. rocess is carried out. referen e may e made to the accompanying description and dra. .ings wherein the design to be created on the printing member is shown, by way of example, as a circle. It is. to be understood, however, that the invention is applicable to the production of other designs as well.

Referring to the drawings-.-

Fig. 1 is a diagrammatic view illustrating a dia-. positive upon whichv an opaque design element has been produced.

Fig. 2 is a diagrammatic sectional view illusi e the e i su e of. a dim. to. light through the di -positive and a diffusion she t.

Fig. 3 i e diagrammati view illustrating the ex osed. partially expo ed, and. still sensitive a a of e film after the first exposure.

Figs. 4 and 5 are diagrammatic sectional views showing the film affixed to a glass plate before and after etching.

Fig. 6 is a diagrammatic sectional view showing the etched film in contact with a screen and a source of light directed against the screen.

Fig. '7 illustrates the screened positive of the design element.

In practising this invention to produce a printing member, adapted especially to printing color designs on fabrics and the like, a diapositive 20, comprising a transparent member upon which a given opaque design element. 2i has been produced, is prepared in any suitable manner. In the dark under proper safelight conditions, a diffusion sheet 22, such as a translucent cellulose acetate, is inserted between and placed in contact with the diapositive 20 and a light sensitive film 23 (see Fig. 2). An exposure of the film 23 is made by directing light of even intensity through the diapositive 20 and the diifusion sheet 212. In general, the film 23 will be exposed in certain areas 2-4 where the light rays pass through the transparent member 20 and the dif fusion sheet 22, while other areas 25. will remain sensitive due to the failure of light rays to pass through the opaque design elements 21. The scattering effect, however, of the diffusion sheet 22 creates a partially exposed margin 26, or penumbra, around the still sensitive areas 25, or, in other words, between the exposed areas 24 and the sensitive areas 25 (see Fig. 3)..

The film is then developed. and etched. In the drawings, however, the film 23 is shown as a type having an anti-halation backing 21. It should he understood that the present invention does not in any way depend upon the specific type film used and, therefore, the use of an antiha1ation film will be dictated by factors totally unrelated to the present process. In this invention, however, the film is subjected to two separate exposures. If, therefore, the use of an an.ti-ha1ation film is deemed advisable in a particular instance, steps should be taken to prevent the anti-halation layer from being washed off during the developing and etching operations in order to preserve it for the second exposure. Toward this end, therefore, the back of the film 23 having the anti-halation backing 21 is affixed to a glass plate 28 (see Fig. 4) whose surface has been coated with a waterproof adhesive 29. While adhered to the glass plate the film is developed and placed in an etching or reversing acid and copper chloride, which has the properties of dissolving the blackened silver corresponding to the exposed areas 24 of the film, but leaves intact the unexposed areas 25 and the partially exposed margin 26 in relief (see Fig. The film 23 is, thereafter, washed to remove the etching solution and thoroughly dried, still under safelight conditions, and removed from the glass plateZS. Obviously, if film without an anti-halation backing were employed, it would be unnecessary to afiix the film to the glass plate before the developing and etching operations.

After developing and etching, a screen 35 of proper line ruling is selected and placed in contact with the emulsion side of the film 23. The second exposure is made by directing light of even intensity through the screen 30 (see Fig. 6), thereby exposing the still sensitive areas 25 of the film except where the screen ruling prevents exposure. The film is then developed for the second and final time and placed in a hardening or fixing bath to prevent any further exposure, thereby terminating the need for further safelight conditions.

As previously stated, the partially exposed margin 26, which was created'by the scattering effect of the light rays passing through the diffusion' sheet 22, had been insufiiciently exposed during the first exposure to be affected by the etching process and, hence, was left in relief along with the sensitive areas 25 (see Fig. 5). The partially exposed margin 26 was, however, sufficiently exposed during the first exposure so as to appear to be unaffected by the second exposure through the screen, that is to say, the ruling of screen does not break up the margin 26 as it does the body of the design elements. A solid, unbroken outline 3! is thus created around the reproduced design elements 32 on the film 23, which, by a process well known in the art, can

be etched onto the actual printing surface to,

produce continuous bleed lines around the ink carrying cells comprising the design elements.

Since the width of the outline 3| is proportional to the thickness of the diffusion sheet 22 employed, it should be obvious that the width of the outline can be increased by using a diffusion sheet of greater thickness and, conversely, decreased by using a diffusion sheet of lesser thickness.

Having thus described my invention what I claim is:

1. In a process for producing a printing member, the series of steps for establishing an outline around the contour of a given design on the printing member from an opaque reproduction of the design which include inserting a difiusion sheet between the opaque reproduction of the design and a film carrying a light sensitive emulsion, exposing the film by directing light against the opaque reproduction, the diffused light producing a partially exposed border around the still sensitive areas of the film, developing the film, removing the emulsion from the fully exposed areas of the film, but leaving intact the still sensitive areas and the partially exposed border, exposing the still sensitive areas and the partially exposed border through a screen, and developing and fixing the film to create a screened positive of the design to be printed.

2. In a process for producing a printing member, the series of steps for establishing an outline of variable width around the contour of the design to be printed from an opaque reproduction of the design, which include inserting a diffusion'sheet of predetermined thickness between the opaque reproduction of the design and a film carrying a light sensitive emulsion, exposing the film by directing light against the opaque reproduction, the diffused light producing a partially exposed. border around the still sensitive areas of the film, developing the film, removing the emulsion from the 'fully exposed areas of the film, but leaving intact the partially exposed border, exposing the still sensitive areas and partially exposed border through a screen, and developing and fixing the film to create a screened positive of the design to be printed.

3. In a process for producing a printing member, the series of steps for establishing an outline around the contour of a given design on the' printing member from a photographic reproduction of the design including exposing a film carrying a light sensitive emulsion by directing light through the photographic reproduction and. a light diffusing layer between the photographic reproduction and the film, the diffused light creating a partially exposed border around the still sensitive areas of the film, etching with a solution which does not affect the partially ex posed border to remove the emulsion from the fully exposed areas of the film, but leaves intact the still sensitive areas and the partially exposed border, exposing the still sensitive areas and the partially exposed border of the film through a screen, and developing and fixing the film to create a screened photographic printing member.

4. In a process for producing a printing member, theseries of steps for establishing an outline around the contour of a given design on the printing member which include creating a diapositive of the design to be printed, inserting a diffusion sheet between the diapositive and a light sensitive film, exposing the film by directing light through the diapositive, the diffused light forming a partially exposed border around the still sensitive areas of the film, developing the film, immersing the film in an etching bath which does not afiect the said border to remove the fully exposed areas of the film, but leaves intact the still sensitive areas and the partially exposed border, exposing the still sensitive areas of the film through a screen, and developing and fixing the film to create a screened positive of the design elements to be printed. I I

5. In a process for producing a printing member, the series of steps for establishing an outline around the contour-of 'a given design on the printing member which include creating a dia positive of the design to be printed, inserting a diffusion sheet between the .diapositive and an anti-halation film, exposing the film by directing light through the diapositive, the diffused light forming a partially exposed border'around the still sensitive areas of the film, preserving'the anti-halation layer, developing the film, immersi'n'g the film in an etching solution which does not affect the said border to remove the fully exposed areas of the film, but leaves intact the still sensitive areas and the partially exposed border, exposing the still sensitive areas and the partially exposed border of the film through a screenj-a'nd developing and fixing the film to create a screened positive of the design elements to be printed.

6. In a process for producing a printing memher, the series of steps for establishing an outline around the contour of a givendesign'on the printing member from a diapositive of the'designto be printed inserting a diffusion sheet between the di p s ti e and a film ca y ng alight sensil tive emulsion and having an anti-halation backing, exposing the film by directing light through the diapositive, the diffused light forming a partially exposed border around the still sensitive areas of the film, aflixing the anti-halation backing of the film to a Waterproof adhesive coating on a plate, developing the film, immersing the plate with the film in an etching solution which does not affect the said border to remove the emulsion from the fully exposed areas of the film, but leaves intact the still sensitive areas and the partially exposed border, exposing the film through a screen, and developing and fixing the film to create a screened positive of the design elements to be printed.

OWEN G. DOI-IERTY.

6 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,859,620 Dyer May 24, 1932 2,175,194 Huggins Oct. 10, 1939 FOREIGN PATENTS Number Country Date 650,152 Germany Sept. 25, 1937 

1. IN A PROCESS FOR PRODUCING A PRINTING MEMBER, THE SERIES OF STEPS FOR ESTABLISHING AN OUTLINE AROUND THE CONTOUR OF A GIVEN DESIGN ON THE PRINTING MEMBER FROM AN OPAQUE REPRODUCTION OF THE DESIGN WHICH INCLUDE INSERTING A DIFFUSION SHEET BETWEEN THE OPAQUE REPRODUCTION OF THE DESIGN AND A FILM CARRYING A LIGHT SENSITIVE EMULSION, EXPOSING THE FILM BY DIRECTING LIGHT AGAINST THE OPAQUE REPRODUCTION, THE DIFFUSED LIGHT PRODUCING A PARTIALLY EXPOSED BORDER AROUND THE STILL SENSITIVE AREAS OF THE FILM, DEVELOPING THE FILM, 